Improvement of spin polarization and spatial uniformity in atomic magnetometers with reflection optimization

In this study, we presented a novel reflective spin-exchange relaxation-free (SERF) atomic magnetometer that enhances the magnetometer's spin polarization and spin polarization spatial uniformity, thereby improving its performance and stability. We derived a comprehensive spin polarization model and conducted simulations to demonstrate the positive impact of the reflective configuration on spin polarization and its spatial uniformity. A diminishing marginal effect of increasing the reflection ratio as the incident optical power increases was observed. Experimental designs were employed to obtain spin polarization information, validating the accuracy and effectiveness of the simulated conclusions. Utilizing the core parameter of long-term sensitivity as the primary criterion for selecting the transmission-to-reflection ratio in the reflective configuration. The experiments yielded a minimum long-term sensitivity of 14.9±5.9 fT/Hz^1/2 (@31.5 Hz) and an optimal single-shot magnetic field measurement sensitivity of 10.0 fT/Hz^1/2 (@31.5 Hz). These results supported the viewpoint of selecting intermediate levels of transmission-to-reflection ratio and incident light power. Moreover, the experiments verified that the reflective magnetometer outperformed the conventional magnetometer. Further research on such reflective magnetometers will contribute to advancing magnetometer system performance and stability, with significant implications for future applications in bio-magnetic measurements.